Nested form not saving user_id despite proper setup

I'm building a site that has Payouts. Payouts have only one attribute: year.

However, there are many awards per Payout. Awards belong to a Payout and a User. Users and Payouts both have many awards.

I'm not having any issues getting the awards associated with the Payout they're added to, however, I cannot for the life of me get the user_id set for an award when using the nested form for Awards on the Payout form. I used Railscast #196 revised as my starting point and my site is running Rails 3.2. I'm at a complete loss of what to do because as far as I can tell, I'm doing everything right.

I'm guessing it's something stupid/little I'm overlooking so any help would be appreciated.

Adding an award from the /awards/new action works fine and associates the chosen User record no problem. However, when submitting from the Payouts new/edit form, the user_id is not inserted/updated ever and results in errors when I attempt to call the award.user.display_name field. I have no idea what I'm doing wrong because as far as I can tell, I've set this up correctly. Awards are being associated with payouts so that's fine...I just can't figure out how to get the user_id field on the award set when creating an award through the Payout's nested Award form.

However, when I go to edit a Payout, none of the associated Awards are displayed on the form. Again...I'm not sure what I'm doing wrong as I followed the Railscast and even went back to a 2.3 app I built years ago to see if I forgot something and, as far as I can tell, have not. :-/